1. Field of the Invention
This invention is directed to apparatuses and methods for carrying out cargo handling and rescues in a body of water..
More particularly, this invention is directed to semi-submersible pylons, functioning as xe2x80x9cSea Cranesxe2x80x9d that can, for example, be deployed at sea from marine vessels or drilling or oil production platforms. These sea cranes are stable submerged buoyancy apparatuses that serve to transfer objects in open sea from one surface vessel to another or from one vessel into or from the sea and to control or maintain such objects while under the stable management of the sea cranes. The sea cranes can stably and safely transfer cargoes between surface vessels, control or maintain, and safely transfer to or from mother ships, submersible vehicles or free floating objects even in the roughest seas.
This invention is also directed to methods for handling cargo at sea, including the transfer of cargo between surface vessels and between a surface vessel and the sea. This invention is also directed to apparatuses and methods employing semi-submersible pylons for effecting rescue of persons at sea.
2. Brief Description of Background Art
Cargo transfer of any type at sea has always been plagued with difficulty in rough seas and high winds. Even smooth waters present collision hazards when bringing surface vessels alongside to transfer cargo at sea. Similarly, when a surface vessel approaches a floating object for pickup at sea, collisions between object and vessel threaten. But stormy conditions compound the hazards even with the best equipment and the most skilled personnel. Launch, recovery, control and maintenance of autonomous or unmanned underwater vehicles (AUV or UUV), remotely operated vehicles (ROV), and manned submersibles is a case in point, in which mother ships without access to the present invention have difficulties with stormy conditions. Smooth waters provide opportunity for easy rescue by boat or helicopter. But stormy conditions risk the best equipment and the most skilled and heroic personnel.
U.S. patent application Ser. No. 09/912,287, filed by the inventor named in this CIP application, discloses a submerged buoyancy rescue pylon. The inventor is not aware of prior art related to the present invention.
An object of the present invention is to enable safer transfers of cargoes or people between ships under way in open sea.
Another object of the present invention is to enable safer transfers of cargoes or people between ships and water in open sea.
Another object of the present invention is to enable significant increases of rough water dive time for manned or unmanned submersibles or divers.
Another object of the present invention is to enable control and powering of ROV devices independently of a mother ship.
Another object of the present invention is to enable safer sea rescues under sea and weather conditions that would otherwise be difficult or impossible.
The foregoing objects of the invention and others as well are realized by a floating apparatus for transferring objects in a body of water from one surface vessel to another, the apparatus comprising: a slender elongated pylon; a cargo support at a first end of the pylon; a variable buoyancy chamber on the pylon between the first end of the pylon and a second end of the pylon; ballast carried by the pylon at the second end thereof, the ballast being of sufficient mass and being spaced from the variable buoyancy chamber by a sufficient distance to create a righting moment about the buoyancy chamber and establish an upright orientation of the pylon in the body of water with the cargo support disposed above the surface of the water and the ballast disposed below the surface of the water; and means for varying the buoyancy of the buoyancy chamber so as to maintain a desired submersion depth of the buoyancy chamber in the body of water.
The objects of the invention are also realized by an apparatus for rescuing persons from a body of water, the apparatus comprising: an elongated pylon; a compartment at a first end of the pylon for accommodating persons rescued from the body of water; a variable buoyancy flotation device at a second end of the pylon; ballast carried by the pylon and movable from a first position between the ends of the pylon to a second position extended beyond the second end of the pylon; annd means for effecting movement of the ballast from the first position to the second position to thereby establish an upright orientation of the pylon in a body of water with the compartment disposed above the surface of the water and the ballast disposed below the surface of the water varying the buoyancy of the flotation device so as to maintain a desired submersion depth of the flotation device in the body of water.
The objects of the invention are also realized by a method for handling cargo in a body of water, the method comprising the steps of: placing cargo at a first end of a slender elongated pylon deployed into the water, the pylon having a variable buoyancy chamber located between the first end and a second end of the pylon; applying a righting moment to the pylon that orients the pylon upright in the water such that (1) the first end of the pylon is disposed above the surface of the water and (2) the buoyancy chamber and the second end of the pylon are disposed below the surface of the water; and varying the buoyancy of the buoyancy chamber so as to maintain a desired submersion depth of the buoyancy chamber in the water while maintaining the first end of the pylon disposed above the surface of the water.
The present invention incorporates a high upright floating pylon with a cargo compartment at the top and a long narrow portion of the pylon above water with a submerged variable buoyancy compartment located on the pylon a distance above a ballast at the lower end of the pylon. The un-submerged portion of the pylon is designed slender to minimally change buoyancy due to wave action and to be high enough for the top thereof to clear the tallest wave crest. The variable buoyancy compartment is designed to be below water at all times and high enough above the ballast that a pylon righting moment is created by a couple between the center of buoyancy of that chamber and the center of gravity of the ballast. This righting moment is made great enough to create a stable cargo compartment high above the highest waves. The buoyancy of the submerged buoyancy compartment is varied by enlarging and reducing the volume of the compartment or by taking in and discharging water ballast, to maintain the upright pylon at its design waterline. The volume variation or purging of water ballast of the submerged buoyancy compartment is effected by an air compressor or release of compressed gas that maintains the pylon waterline at sea level just above the compartment.
The added sea crane embodiments of the sea crane are distinguishable from the rescue pylon described in the aforementioned application Ser. No. 09/912,287 in several ways. The erect rescue pylon supports cargo at the top of the pylon in a stable mode. But, if a surface vessel affixes a tag line to the top of the pylon and, while fending off the pylon at the waterline, the vessel takes in the tag line, tilting the pylon against the righting moment between submerged buoyancy and deeper pylon ballast, the cargo and the top of the pylon begin to move synchronously with the surface vessel. As the cargo and tilting pylon top approach the surface vessel, the amplitude of cargo motion matches that of the vessel avoiding a collision hazard between cargo and deck or vessel side during transfer. The transfer of cargo from surface vessel to pylon top reverses the above process. The sea crane concept can be applied to safely transfer cargoes between surface vessels or control and maintain and eventually safely transfer objects to or from mother ships, fixed structures, submersible vehicles or free floating objects while in the roughest seas.
Objects and advantages of several embodiments of the present invention are disclosed herein. Still further objects and advantages will become apparent from a consideration of the ensuing description and accompanying drawings.